Precast concrete panels have improved the acoustics for the BBC National Orchestra of Wales’ new home in Cardiff.
BBC Hoddinott Hall, a new purpose-built home for the BBC National Orchestra of Wales on the Wales Millennium Centre site, opened at the end of January to a fanfare of music.
Construction work had started back in April 2007 on reclaimed land in the former Victorian docklands at Cardiff Bay. The Cardiff office of Capita Architecture – which also worked on the Wales Millennium Centre – along with engineering consultant URS, designed the new building. Its structure and cladding comprise of slate, timber and stainless steel. The main structure is a steel frame building over an in situ single-storey car park.
The hall has a deep truss primary roof structure, which encompasses the lighting and sound equipment zone at ceiling level. Over 3,400m2 of bespoke prestressed, precast concrete panels have been used in the rehearsal and recording facility. Concrete’s mass and damping qualities were used to achieve good acoustic performance. This was done with concrete panels that were designed and manufactured to provide the inner and outer leaf construction of the auditorium walls and roof and form a complete acoustic enclosure.
The double 150mm thick skin of concrete was attached via bespoke fixings to the steel frame, which itself was supported on acoustic bearings to acoustically isolate the whole auditorium from its foundations. Milbury Systems supplied the precast concrete panels for the auditorium and adjacent building for principal contractor Sir Robert McAlpine.
The number of joints in the acoustic envelope was reduced by using extra long units up to 8.5m long. The acoustic efficiency was enhanced by the standard tongue and grooved panel joint details. “Dimensionally this was a complex building to design panels for,” says Milbury chief engineer Ian Lovering. “The bespoke panels required modification of our standard factory equipment but minimised the amount of joints, which was paramount for the acoustic function.”
Prestressing the units enabled easier handling on site and meant that they could accommodate more openings within the walls of the hall without the need for secondary steel trimming. Substantial fixed equipment and acoustic sliding timber panels were hung from the wall panels.
The bespoke panels required modification of our standard factory equipment but minimised the amount of joints, which was paramount for the acoustic function
Ian Lovering, chief engineer, Milbury
The chorus and auditorium seating also featured prestressed units. All of the 350 panels and seating terrace units for the scheme were manufactured at Milbury’s concrete production facility in Lydney, Gloucestershire during the autumn of 2007. Units were delivered to a waiting yard close to the site and then delivered to accord with the erection programme.
The constructed walls have been clad at low level in acoustic timber panelling and left exposed in the remainder of the hall. In addition to the grand new performance hall that seats up to 350, the building also has office and rehearsal space and a recording studio.
MOVING STUFF: BBC ORCHESTRA RELOCATION
Since 1967 the National Orchestra of Wales has been based in Studio 1 at the BBC Studios in Llandaff, Cardiff.
The Orchestra has long out-grown this home and the new purpose-built studio has been added as Phase 2 of Wales’ Millennium Centre complex in Cardiff Bay.
BBC Hoddinott Hall will now be the Orchestra’s base where all its rehearsals and studio recordings will be made.